Our overall objectives in this project are to increase our understanding of the regulation of individual nephron glomerular filtration rates by exploiting the unique structural arrangement of the avian kidney. We are particularly interested in several aspects of this broad problem: 1) the more precise determination of the effects of certain factors, such as sodium chloride and antidiuretic hormone, on the regulation of single nephron glomerular filtration rates (SNGFR) within the different nephron populations of the avian kidney; 2) the intrarenal patterns of blood flow and their regulation by factors such as antidiuretic hormone; and, 3) the effects of alterations in the function of individual nephrons on the renal concentrating and diluting mechanism. BIBLIOGRAPHIC REFERENCE: Irish, J.M. and W.H. Dantzler. PAH transport and fluid absorption by isolated perfused frog proximal renal tubules. Am. Journ. Physiol. 230: 1509-1516, 1976.